Let's use less cryptic names. Both are redirection pools, one used for NAT the other for route targets. Why not rpool_nat and rpool_route?

The same question as for netlink: how about some better names like rpool_nat and rpool_route? Or even better, since there is a new which, maybe we could have a new enum (I see that currently which abuses the enum for rule type) for rpool type and have here an array?

Do you mean for the netlink name (so say PF_RT_RPOOL_NAT / PF_RT_RPOOL_ROUTE) or for the structure pf_krule fields?

The former I'm happy to change (well, the PF_RT_NAT one anyway, PF_RT_RPOOL is already in live code. Admittedly only on the main branch, so we could still get away with changing it, but still), but the latter is what OpenBSD uses and I'd prefer to not create conflicts unnecessarily.

As above, I'd prefer to keep this close to the OpenBSD code if possible.
I also don't think we need an array we're extremely unlikely to ever extend.

PF_RT_RPOOL_NAT and PF_RT_RPOOL_ROUTE sound good to me. The _RPOOL part nicely groups them together and shows what the underlying struct is about, and _ROUTE and `_NAT clearly show what each pool is used for.

Admittedly only on the main branch, so we could still get away with changing it, but still.

So there was no release yet. If you have any testing systems which must undergo upgrades you could add the new netlink variable, read both, keep it for a few weeks, delete it later.

but the latter is what OpenBSD uses and I'd prefer to not create conflicts unnecessarily.

OpenBSD does not use netlink, what do you mean? There are

struct pf_rule {
…
	struct pf_pool		 nat;
	struct pf_pool		 rdr;
	struct pf_pool		 route;
…
}

in OpenBSD, so we could easily do:
PF_RT_RPOOL_NAT -> struct pf_pool nat
PF_RT_RPOOL_ROUTE -> struct pf_pool route

And that leaves me free to pursue
PF_RT_RPOOL_RDR -> struct pf_pool rdr
one day.

The OpenBSD argument is good. Let's keep their names for struct pf_krule members.

OpenBSD does not use netlink, what do you mean? There are

I was talking about the struct pf_krule members, not the netlink variable name here.
I think we're in agreement. I'll work on updating the netlink names.